Advanced electronic device structures using semiconductor structures and superlattices

Abstract

Semiconductor structures and methods for forming those semiconductor structures are disclosed. For example, a p-type or n-type semiconductor structure is disclosed. The semiconductor structure has a polar crystal structure with a growth axis that is substantially parallel to a spontaneous polarization axis of the polar crystal structure. The semiconductor structure changes in composition from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis to induce p-type or n-type conductivity.

What is claimed is: 
     
       1. A method of forming a p-type or n-type semiconductor structure, the method comprising:
 growing along a growth axis a semiconductor having a polar crystal structure, the growth axis being substantially parallel to a spontaneous polarization axis of the polar crystal structure; and 
 changing a composition of the semiconductor monotonically from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis to induce p-type or n-type conductivity. 
 
     
     
       2. The method of  claim 1 , wherein the composition of the semiconductor comprises:
 at least two types of metal atom cations; and 
 a non-metal atom anion. 
 
     
     
       3. The method of  claim 2 , wherein the non-metal atom anion is nitrogen or oxygen. 
     
     
       4. The method of  claim 2 , wherein changing the composition of the semiconductor comprises: changing a molar fraction of one or more of the at least two types of metal atom cations in the composition along the growth axis. 
     
     
       5. The method of  claim 1 , wherein the p-type conductivity is induced by:
 growing the semiconductor with a cation-polar crystal structure and changing the composition of the semiconductor monotonically from a WBG material to a NBG material along the growth axis; or 
 growing the semiconductor with an anion-polar crystal structure and changing the composition of the semiconductor monotonically from a NBG material to a WBG material along the growth axis. 
 
     
     
       6. The method of  claim 1 , wherein the n-type conductivity is induced by:
 growing the semiconductor with a cation-polar crystal structure and changing the composition of the semiconductor monotonically from a NBG material to a WBG material along the growth axis; or 
 growing the semiconductor with an anion-polar crystal structure and changing the composition of the semiconductor monotonically from a WBG material to a NBG material along the growth axis. 
 
     
     
       7. The method of  claim 1 , wherein the polar crystal structure is a polar wurtzite crystal structure. 
     
     
       8. The method of  claim 1 , wherein the composition of the semiconductor is changed in a stepwise manner along the growth axis. 
     
     
       9. The method of any  claim 1 , wherein the composition of the semiconductor is selected from group-III metal nitride compositions. 
     
     
       10. The method of  claim 1 , wherein the composition of the semiconductor is selected from the following:
 aluminium gallium nitrides (Al x Ga 1-x N) where 0≦x≦1; 
 aluminium gallium indium nitrides (Al x Ga y In 1-x-y N) where 0≦x≦1, 0≦y≦1 and 0≦(x+y)≦1; and 
 magnesium zinc oxides (Mg x Zn x-1 O) where 0≦x≦1. 
 
     
     
       11. The method of  claim 1 , further comprising:
 including impurity dopants in the composition of the semiconductor to enhance the induced p-type or n-type conductivity. 
 
     
     
       12. A method of forming a complex semiconductor structure, the method comprising: forming two or more contiguous semiconductor structures and/or semiconductor superlattices, wherein the contiguous semiconductor structures and/or semiconductor superlattices are each formed according to the method of  claim 1 . 
     
     
       13. The method of  claim 12 , further comprising flipping a polarity-type of material between two of the two or more contiguous semiconductor structures. 
     
     
       14. The method of  claim 12 , wherein a first of the two or more contiguous semiconductor structures has a larger change in composition along the growth axis and a second of the two or more contiguous semiconductor structures has a smaller change in composition along the growth axis. 
     
     
       15. A p-type or n-type semiconductor structure having a polar crystal structure with a growth axis that is substantially parallel to a spontaneous polarization axis of the polar crystal structure, the semiconductor structure having an induce p-type or n-type conductivity resulting from a monotonic change in composition from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis. 
     
     
       16. A complex semiconductor structure comprising two or more contiguous semiconductor structures in accordance with  claim 15 .